Example 1
- Carbs: 40 g
- Fiber: 12 g
28 g
40 g carbs minus 12 g fiber gives 28 g net.
Net carbs calculator
Type carbohydrate grams and fiber grams from the same serving. The calculator subtracts and floors at zero. Forty grams minus 12 g is 28 g net.
Net = max(0, carbs - fiber). Grams from a kcal percent live on the carb calorie calculator.
Result
Carbs (g) and Fiber (g). Net carbs shows up here.
How it works
Net carbs come from two label numbers: you subtract fiber from carbs. Forty grams and 12 g of fiber give 28 g. Fifty minus 8 gives 42 g. Twenty-five minus 6 gives 19 g. Thirty minus 30 lands on 0 g, because the code does not show a negative. Sixty minus 15 is 45 g. Twenty minus 4 is 16 g. Thirty-five minus 20 is 15 g. Forty-five minus 10 is 35 g.
People arrive looking for “keto carbs” and get plain subtraction. The neighboring carb calorie card starts from kilocalories and a percent, then divides by 4. That page has no fiber field. Sugar plus fat multiplies sugar grams by 4 and also leaves fiber alone. Here you work from serving grams, not from a daily percent.
The US switch treats the entries as ounces and multiplies by 28.349523125, then subtracts in grams. If both numbers use the same unit, the pair 40 and 12 is the same subtraction as 40 g and 12 g. Alcohol and sugar alcohols do not enter the formula. The calculator does not guess a package net figure when you type only one mass.
Typed 0 fiber is zero and leaves the carbs unchanged. An empty field does not stand in for zero. When fiber is larger than carbs, the result is 0 g, not a minus. A US label is often counted that way, but this page does not read a barcode. You type both numbers yourself.
Treat 28 g as a label exercise for class, not as a keto plan and not as a finding. Type 40 and 12, click Calculate, and check 28 g. Then try 30 and 30 to see the floor at zero. Fiber: Fiber grams from that same serving.
12 g taken from 40 g of carbs leaves 28 g net. Not a kcal conversion from a daily percent.
How to use
- Type carbohydrates from a label or a recipe, in grams or ounces matching the units switch.
- Type fiber from the same serving, in the same unit. Typed 0 is allowed and subtracts nothing.
- Click Calculate. 40 g of carbs and 12 g of fiber give 28 g net.
- When fiber is greater than or equal to carbs, the result is 0 g, not a negative.
- Daily grams from a kcal percent live on the carb calorie calculator. This page stays with fiber subtraction.
Formula
net = max(0, carbs - fiber)
Not kcal from a TDEE percent.
Net carbs as carbs minus fiber
From the same serving you subtract fiber from carbohydrate and floor at zero. Forty grams minus 12 g is 28 g net.
- net
- max(0, carbs − fiber). 40 − 12 = 28. If fiber exceeds carbs, the result is 0, not a negative number.
- Fiber
- Fiber grams from that same serving. 12 g taken from 40 g of carbs leaves 28 g net. Not a kcal conversion from a daily percent.
- carbs
- Carbohydrate grams from the label, before the subtraction. The Carbs (g) field at 40 with fiber 12 ends at 28 g net.
Examples
Example 2
- Carbs: 50 g
- Fiber: 8 g
42 g
50 minus 8 gives 42 g net.
Example 3
- Carbs: 30 g
- Fiber: 30 g
0 g
30 minus 30 gives 0 g, because the result does not go below zero.
Example 4
- Carbs: 25 g
- Fiber: 6 g
19 g
25 minus 6 gives 19 g net.
Example 5
- Carbs: 60 g
- Fiber: 15 g
45 g
60 minus 15 gives 45 g net.
Example 6
- Carbs: 20 g
- Fiber: 4 g
16 g
20 minus 4 gives 16 g net.
Example 7
- Carbs: 35 g
- Fiber: 20 g
15 g
35 minus 20 gives 15 g net.
Example 8
- Carbs: 45 g
- Fiber: 10 g
35 g
45 minus 10 gives 35 g net.
Frequently asked questions
What do I get at 40 g of carbs and 12 g of fiber?
28 g net, because 40 minus 12. At 50 g and 8 g of fiber it is 42 g.
What happens when fiber equals carbs?
At 30 g and 30 g the result is 0 g. The formula floors at zero, so you will not see a minus.
Does this calculator turn 50% of 2200 kcal into grams?
No. A daily percent divided by 4 lives on the carb calorie calculator. Here you subtract fiber from serving grams.
Is typed 0 fiber the same as an empty field?
No. Typed 0 leaves the carbs unchanged. An empty field does not stand in for zero and does not subtract.
What is 25 g and 6 g, and what is 60 g and 15 g?
19 g and 45 g. The same subtractions as on the page examples.
Do ounces change 28 g for the same serving?
No, if both numbers match the same 40 g and 12 g. The switch multiplies by 28.349523125 and subtracts in grams.
Do sugar alcohols come off net on this page?
No. The formula knows only carbs and fiber. Other label subtractions are not here.
How is net different from sugar-and-fat kcal?
Sugar plus fat multiplies grams by 4 and 9. Here you subtract fiber, with no kilocalories.
What is 20 g minus 4 g, and 35 g minus 20 g?
16 g and 15 g. 45 minus 10 is 35 g. Always carbs minus fiber.
Is 28 g net a keto plan or a finding?
It is label subtraction on paper. The calculator does not build a meal plan and does not make a diagnosis.
Knowledge sources
Net = max(0, carbs − fiber). This is subtraction, not a glycaemic index.
Page updated in 2026.